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To compare the diagnostic performance of two different sets of magnetic resonance imaging (MRI) for the detection of subchondral erosions in the sacroiliac joints regarding the application of fat-water separation techniques when acquiring T1-weighted (T1w) images, using multi-detector computed tomography (MDCT) as the reference standard. We retrospectively included 31 consecutive patients having or being suspected for axial spondyloarthritis (SpA) assessed using both MRI and MDCT. Three sets of images were independently assessed for the presence of erosions by two musculoskeletal radiologists (R1, R2): (1) MRI with standard T1w without fat suppression, (2) MRI with both T1w with and without fat suppression, and (3) MDCT. The diagnostic performance of both sets of MRIs was assessed using MDCT as the referent. The assessment of T1w images with fat suppression substantially increased sensitivity (76% vs. 63% R1; 70% vs. 60% R2), specificity (97% vs. 84% R1; 96% vs. 81% R2), positive predictive value (85% vs. 45% R1; 81% vs. 40% R2), and overall accuracy (94% vs. 80% R1; 92% vs. 77% R2) in the detection of erosions when compared to the assessment using T1w images without fat suppression. The assessment of T1w images with fat suppression substantially improves the diagnostic performance of MRI in the detection of erosions in the sacroiliac joints. • The presence of erosions in the sacroiliac joints may influence the decision on the diagnosis of axial spondyloarthritis. • T1w fat-suppressed MR imaging relatively increases the contrast between the joint space (high signal) and the adjacent subchondral bone (low signal), potentially improving the detection of erosions in the sacroiliac joints. • T1w fat-suppressed images improve the diagnostic performance of MRI in the detection of erosions in the sacroiliac joints compared to T1w without fat suppression, using MDCT as the reference.

The perihepatic space is frequently involved in a spectrum of diseases, including intrahepatic lesions extending to the liver capsule and disease conditions involving adjacent organs extending to the perihepatic space or spreading thanks to the communication from intraperitoneal or extraperitoneal sites through the hepatic ligaments. Lesions resulting from the dissemination of peritoneal processes may also affect the perihepatic space. Here we discuss how to assess the perihepatic origin of a lesion and describe the magnetic resonance imaging (MRI) features of normal structures and fluids that may be abnormally located in the perihepatic space. We then review and illustrate the MRI findings present in cases of perihepatic infectious, tumor-related, and miscellaneous conditions. Finally, we highlight the value of MRI over computed tomography.

Primary lymphedema, a rare disease, has a genetic cause in ~40% of patients. Recently, loss-of-function mutations in PIEZO1, which encodes the mechanotransducer protein PIEZO1, were described as causing primary lymphedema, when gain-of-function PIEZO1 mutations were attributed to dehydrated hereditary stomatocytosis type-1 (DHS), a dominant red cell hemolytic disorder, with ~20% of patients having perinatal edema. Lymphedema was diagnosed in a 36-year-old man from a three-generation DHS family, with a PIEZO1-allele harboring 3 missense mutations in cis. Four affected family members had severe fetal and neonatal edema, most severe in the proband, whose generalized edema with prevailing ascites resolved after 8 months. Our patient's intermittent lower limb-lymphedema episodes during hot periods appeared at puberty; they became persistent and bilateral at age 32. Clinical Stemmer's sign confirmed lymphedema. Lower leg lymphoscintigraphy showed substantial dermal backflow in both calves, predominantly on the right. Noncontrast magnetic resonance lymphography showed bilateral lower limb lymphedema, dilated dysplastic lymphatic iliac, and inguinal trunks. Exome-sequencing analysis identified no additional pathogenic variation in primary lymphedema-associated genes. This is the first description of well-documented lymphedema in an adult with PIEZO1-DHS. The pathophysiology of PIEZO1-associated primary lymphedema is poorly understood. Whether it infers overlapping phenotypes or different mechanisms of gain- and loss-of-function PIEZO1 mutations deserves further investigation.

International audience

Primary sclerosing cholangitis (PSC) is a chronic inflammatory disorder affecting the bile ducts and is characterized by biliary strictures, progressive liver parenchymal fibrosis, and an increased risk of hepatobiliary malignancies primarily cholangiocarcinoma (CCA). PSC may lead to portal hypertension, liver decompensation, and liver failure with the need for liver transplantation. Magnetic resonance imaging (MRI)/magnetic resonance cholangiopancreatography (MRCP) are considered the imaging standard for diagnosis and follow-up in patients with PSC. Currently, there are no universally accepted reporting standards and definitions for MRI/MRCP features. Controversies exist about the definition of a high-grade stricture and there is no widely agreed approach to their management. The members of the MRI working group of the International Primary Sclerosing Cholangitis Study Group (IPSCSG) sought to define terminologies and reporting standards for describing MRI/MRCP features that would be applied to diagnosis and surveillance of disease progression, and potentially for evaluating treatment response in clinical trials. In this extensive review, the technique of MRI/MRCP and assessment of image quality for the evaluation of PSC is briefly described. The definitions and terminologies for severity and length of strictures, duct wall thickening and hyperenhancement, and liver parenchyma signal intensity changes are outlined. As CCA is an important complication of PSC, standardized reporting criteria for CCA developing in PSC are summarized. Finally, the guidelines for reporting important changes in follow-up MRI/MRCP studies are provided. KEY POINTS: • Primary sclerosing cholangitis is a chronic inflammatory disorder affecting the bile ducts, causing biliary strictures and liver fibrosis and an increased risk of cholangiocarcinoma. • This consensus document provides definitions and suggested reporting standards for MRI and MRCP features of primary sclerosing cholangitis, which will allow for a standardized approach to diagnosis, assessment of disease severity, follow-up, and detection of complications. • Standardized definitions and reporting of MRI/MRCP features of PSC will facilitate comparison between studies, promote longitudinal assessment during management, reduce inter-reader variability, and enhance the quality of care and communication between health care providers.

International audience; OBJECTIVE. The purpose of this multicenter retrospective study was to assess the MRCP features of Caroli disease (CD).MATERIALS AND METHODS. Sixty-six patients were identified from 2000 to 2019. The inclusion criteria were diagnosis of diffuse or localized CD mentioned in an imaging report, presence of intrahepatic bile duct (IHBD) dilatation, and having undergone an MRCP examination. The exclusion criteria included presence of obstructive proximal biliary stricture and having undergone hepatobiliary surgery other than cholecystectomy. Histopathology records were available for 53 of the 66 (80%) patients. Diffuse and localized diseases were compared by chi-square and t tests and Kaplan-Meier model.RESULTS. Forty-five patients had diffuse bilobar CD ((five pediatric patients [three girls and two boys] with a mean [± SD] age of 8 ± 5 years [range, 1–15 years] and 40 adult patients [26 men and 14 women] with a mean age of 35 ± 11 years [range, 20–62 years]) and 21 patients had localized disease (12 men and 9 women; mean age, 54 ± 14 years). Congenital hepatic fibrosis was found only in patients with diffuse CD (35/45 [78%]), as was a “central dot” sign (15/35 [43%]). IHBD dilatation with both saccular and fusiform features was found in 43 (96%) and the peripheral “funnel-shaped” sign in 41 (91%) of the 45 patients with diffuse CD but in none of the patients with localized disease (p < .001). Intrahepatic biliary calculi were found in all patients with localized disease but in only 16 of the 45 (36%) patients with diffuse CD (p < .001). Left liver atrophy was found in 18 of the 21 (86%) patients with localized disease and in none of the patients with diffuse CD (p < .001). The overall survival rate among patients with diffuse CD was significantly lower than that among patients with localized disease (p = .03).CONCLUSION. Diffuse IHBD dilatation with both saccular and fusiform features associated with the peripheral funnel-shaped sign can be used for the diagnosis of CD on MRCP. Localized IHBD dilatation seems to be mainly related to primary intrahepatic lithiasis.

Background & Aims Low-phospholipid-associated cholelithiasis (LPAC) syndrome, a rare genetic form of intrahepatic cholelithiasis in adults, is still poorly understood. We report the results of the largest-ever case-control study of patients with LPAC syndrome aiming to assess the prevalence, clinical features, and comorbidities of the disease. Methods We included all LPAC cases diagnosed between 2001 and 2016 in 11 French centres. Controls consisted of all patients who underwent a cholecystectomy for common gallstone disease in a single non-academic centre over 1 year. A logistic regression analysis was used to identify the clinical features associated with LPAC syndrome across several patient strata with increasing levels of diagnostic confidence. The ratio between the incident cases of LPAC syndrome and the total number of cholecystectomies for gallstones was used to assess the relative prevalence of the disease. Results In this study, 308 cases and 206 controls were included. LPAC syndrome accounted for 0.5–1.9% of all patients admitted with symptomatic gallstone disease. Age at first symptoms, Graphical abstract, Highlights • Low-phospholipid-associated cholelithiasis (LPAC) syndrome affects approximately 1% of adults with symptomatic cholelithiasis. • Normal weight, common bile duct stones, and lack of cholecystitis are clinical features significantly associated with this syndrome. • ABCB4 variants in patients with LPAC may be associated with an increased personal or family risk of hepato-biliary cancer.

International audience; GBCA gadolinium-based contrast agent MR magnetic resonance MRC magnetic resonance cholangiography PSC primary sclerosing cholangitis VCTE vibration controlled transient elastography Dear editor, We read with interest the review written by Mahzar and Russo about non-invasive prognostic tests for primary sclerosing cholangitis (PSC) 1. Although rare, PSC is a serious disease, associated with potentially lethal complications, notably cirrhosis and cholangiocarcinoma 2. Liver transplantation is the only curative treatment for PSC and median transplant-free survival is approximately 12-21 years after diagnosis 3. Identification of prognostic factors is essential for tailoring the follow-up strategies and testing new therapeutic modalities in homogeneous groups of PSC patients. As detailed in this review, over the last twenty years, different teams across the world, including ours, have identified several noninvasive prognostic tests for PSC patients 1. First, our team demonstrated in a large retrospective study that liver stiffness measured by vibration-controlled transient elastography (VCTE) was an independent predictive marker of survival in PSC patients 4. Next, we built 2 magnetic resonance (MR) risk scores (with and without gadolinium-based contrast agent (GBCA) administration) 5 , called Anali scores, and showed that they were able to predict adverse outcome-free survival (defined by survival without liver transplantation or cirrhosis

Background and purpose Many artificial intelligence tools are currently being developed to assist diagnosis of dementia from magnetic resonance imaging (MRI). However, these tools have so far been difficult to integrate in the clinical routine workflow. In this work, we propose a new simple way to use them and assess their utility for improving diagnostic accuracy. Materials and methods We studied 34 patients with early-onset Alzheimer's disease (EOAD), 49 with late-onset AD (LOAD), 39 with frontotemporal dementia (FTD) and 24 with depression from the pre-existing cohort CLIN-AD. Support vector machine (SVM) automatic classifiers using 3D T1 MRI were trained to distinguish: LOAD vs. Depression, FTD vs. LOAD, EOAD vs. Depression, EOAD vs. FTD. We extracted SVM weight maps, which are tridimensional representations of discriminant atrophy patterns used by the classifier to take its decisions and we printed posters of these maps. Four radiologists (2 senior neuroradiologists and 2 unspecialized junior radiologists) performed a visual classification of the 4 diagnostic pairs using 3D T1 MRI. Classifications were performed twice: first with standard radiological reading and then using SVM weight maps as a guide. Results Diagnostic performance was significantly improved by the use of the weight maps for the two junior radiologists in the case of FTD vs. EOAD. Improvement was over 10 points of diagnostic accuracy. Conclusion This tool can improve the diagnostic accuracy of junior radiologists and could be integrated in the clinical routine workflow.

Purpose To develop French guidelines by experts to standardize data acquisition, image interpretation, and reporting in rectal cancer staging with magnetic resonance imaging (MRI). Materials and methods Evidence-based data and opinions of experts of GRECCAR (Groupe de REcherche en Radiologie sur le CAncer du Rectum [i.e., Rectal Cancer Imaging Research Group]) and GRECAR (Groupe de REcherche en Chirurgie sur le CAncer du Rectum [i.e., Rectal Cancer Surgery Research Group]) were combined using the RAND-UCLA Appropriateness Method to attain consensus guidelines. Experts scoring of reporting template and protocol for data acquisition were collected; responses were analyzed and classified as “Recommended” versus “Not recommended” (when ≥ 80% consensus among experts) or uncertain (when Results Consensus regarding patient preparation, MRI sequences, staging and reporting was attained using the RAND-UCLA Appropriateness Method. A consensus was reached for each reporting template item among the experts. Tailored MRI protocol and standardized report were proposed. Conclusion These consensus recommendations should be used as a guide for rectal cancer staging with MRI.

To compare the diagnostic performance of two different sets of magnetic resonance imaging (MRI) for the detection of subchondral erosions in the sacroiliac joints regarding the application of fat-water separation techniques when acquiring T1-weighted (T1w) images, using multi-detector computed tomography (MDCT) as the reference standard.We retrospectively included 31 consecutive patients having or being suspected for axial spondyloarthritis (SpA) assessed using both MRI and MDCT. Three sets of images were independently assessed for the presence of erosions by two musculoskeletal radiologists (R1, R2): (1) MRI with standard T1w without fat suppression, (2) MRI with both T1w with and without fat suppression, and (3) MDCT. The diagnostic performance of both sets of MRIs was assessed using MDCT as the referent.The assessment of T1w images with fat suppression substantially increased sensitivity (76% vs. 63% R1; 70% vs. 60% R2), specificity (97% vs. 84% R1; 96% vs. 81% R2), positive predictive value (85% vs. 45% R1; 81% vs. 40% R2), and overall accuracy (94% vs. 80% R1; 92% vs. 77% R2) in the detection of erosions when compared to the assessment using T1w images without fat suppression.The assessment of T1w images with fat suppression substantially improves the diagnostic performance of MRI in the detection of erosions in the sacroiliac joints.• The presence of erosions in the sacroiliac joints may influence the decision on the diagnosis of axial spondyloarthritis. • T1w fat-suppressed MR imaging relatively increases the contrast between the joint space (high signal) and the adjacent subchondral bone (low signal), potentially improving the detection of erosions in the sacroiliac joints. • T1w fat-suppressed images improve the diagnostic performance of MRI in the detection of erosions in the sacroiliac joints compared to T1w without fat suppression, using MDCT as the reference.

Computerized tomography (CT) and magnetic resonance imaging (MRI), particularly MR Enterography, are the standard cross-sectional imaging modalities used to study small bowel involvement in a context of multiorgan disease. Clinical symptoms are generally nonspecific in such cases. Moreover, imaging findings of the different conditions often overlap. However, analysis of the location, distribution of the lesions on the small bowel wall, as well as of the rest of the bowel and of distant organs, may help narrow the spectrum of diagnoses of multiorgan conditions involving both the small bowel and other organs. The purpose of this presentation is to review and illustrate the CT and MRI features of small bowel involvement in systemic disease. Based on the underlying mechanism, we will categorize them as follows: congenital/hereditary, immunologic, infiltrative, vascular, infectious and miscellaneous.

Chylothorax is a rare cause of pleural effusion, secondary to accumulation of lymph in the pleural space. Diagnosis is based on the triglyceride and cholesterol content of pleural fluid obtained with thoracentesis. Because the lymphatic system plays an essential role in fat absorption and immune response, lymphatic leak associated with chylothorax may cause life-threatening malnutrition and immunodeficiency. Chylothorax is usually described as traumatic or nontraumatic. The main cause of chylothorax is traumatic, typically postsurgical, secondary to iatrogenic direct puncture of the thoracic duct during thoracic surgery. Causes of nontraumatic chylothorax include a wide range of differential diagnoses. Lymphoma and thoracic malignancies are the most common causes and are responsible for chylothorax by extrinsic compression or invasion of the thoracic duct. Other rare causes include primary and secondary diffuse lymphatic diseases, responsible for chylothorax by lymphatic vessel wall dysfunction. Imaging the lymphatic system remains a challenge in the days of modern imaging. Nonenhanced MR lymphography is a noninvasive technique based on heavily T2-weighted sequences, thus enabling visualization of the lymphatic circulation. This technique allows diagnosis and differential diagnosis, evaluation of disease severity, and guidance of therapeutic management in nontraumatic chylothorax. Furthermore, it may offer radiologic classification of primary lymphatic diseases on the basis of morphologic features of lymphatic vessels. The authors describe the anatomy and physiology of the thoracic lymphatic system, present the technique of nonenhanced MR lymphography, and discuss pathophysiologic mechanisms and imaging features in different causes of nontraumatic chylothorax. ©RSNA, 2020.

The advanced melanoma is a redoubtable disease which doesn’t give the choice of “sentinel nodes” resection. This surgery is performed widely, with resections of all the vessels above the femoral artery and vein, and the fatty tissue containing the superficial lymphatic vessels and nodes, plus the deep inguinal nodes when the melanoma does affect the leg. The lymphoedema does appear generally very soon after surgery and can be extremely significant. For the upper extremity, wide resection in the axillar region must be also performed, to remove all the tissue around the nodes.